This module provides functions for calculating the path to a map tile at OpenStreetMap out of geographic
coordinates. The path of a tile at OSM has the form "$zoom/$tilex/$tiley.png". The numbering scheme is
documented in the OSM wiki, see the link below.
"lon2tilex($lon,$zoom)"
Returns $tilex for the tile at longitude $lon and zoom level $zoom. The longitude must be in the range
"-180.0 <= $lon < 180.0". The zoom level must be a non-negative integer.
"lat2tiley($lat,$zoom)"
Returns $tiley for the tile at latitude $lat and zoom level $zoom. The latitude must be in the range
"-85.0511 <= $lat <= 85.0511". The zoom level must be a non-negative integer.
"tile2path($tilex,$tiley,$zoom)"
Composes the path to the tile at $tilex, $tiley, and $zoom at the OSM server. $tilex and $tiley must be
integers in the range "0..2**$zoom-1". The supported range of zoom levels depends on the tile server.
The maximum zoom for the Osmarender layer is 17, it is 18 for the Mapnik layer.
"checklonrange($lonmin,$lonmax)"
Checks whether $lonmin and $lonmax are within the allowed range of the longitude argument to "lon2tilex".
Returns "($lonmin, $lonmax)" unchanged if they are ok or corrected values if not.
"checklatrange($latmin,$latmax)"
Checks whether $latmin and $latmax are within the allowed range of the latitude argument to "lat2tiley".
Returns "($latmin, $latmax)" unchanged if they are ok or corrected values if not.